The Trail of Tears refers to the forced relocation of American Indian tribes during the 1890s by the federal government, which uprooted thousands of Cherokee natives from Georgia, Alabama, and Tennessee and marched them west to reside in what is now Oklahoma. Hundreds perished during the march, and thousands more died subsequently due to the effects of relocation.

Braley apologized early on Friday morning, sending another message that explained, "The 'tears' I was referring to were the tears of Cyclone fans. I have removed the tweet & apologize to anyone who was offended."

Braley, who has represented Iowa in the U.S. House since 2007, announced in February that he would seek the Democratic nomination for the U.S. Senate seat currently held by Sen. Tom Harkin, D-Iowa, who has indicated that he will retire when his current term expires in 2015.